Extremely distinct microbial communities in closely related leafhopper subfamilies: Typhlocybinae and Eurymelinae (Cicadellidae, Hemiptera)

Abstract

AO_SCPLOWBSTRACTC_SCPLOWAmong the Hemiptera insects, a widespread way of feeding is sucking sap from host plants. Due to diet poor in nutrients, these insects enter into obligate symbiosis with their microorganisms. However, within the Cicadellidae family, there is a relatively large group of mesophyll feeders - Typhlocybinae that is considered to be devoid of symbiotic companions. In this work, we examine the composition of microorganisms in this subfamily and compare the results with their close relatives - the Eurymelinae subfamily. To study the microbiome, we used high-throughput next-generation sequencing (NGS, Illumina) and advanced microscopic techniques such as transmission electron microscopy (TEM) and fluorescence in situ hybridization (FISH) in a confocal microscope. The Typhlocybinae insects have very poor microbial communities in their bodies, these are mainly facultative microorganisms, such as alphaproteobacteria of the genus Wolbachia or Rickettsia. We detected also the presence of bacteria that can be considered as facultative symbionts e.g. Spiroplasma, Acidocella, Arsenophonus, Sodalis, Lariskella, Serratia, Cardinium and Asaia. On the other hand, the Eurymelinae group is characterized by a large diversity of the microbial communities, similar to those described in other Cicadomorpha. We find obligate co-symbionts involved in the synthesis of essential amino acids such as Sulcia, betaproteobacteria related to genus Nasuia or gammaproteobacteria Sodalis. In other representatives, we observed symbiotic yeast-like fungi from the family Ophiocordycipitaceae and within some genera we discovered Arsenophonus bacteria inhabiting the interior of Sulcia bacteria. Additionally, we investigated the transovarial transmission of obligate symbionts, which occurs via infection of the ovaries of females. IO_SCPLOWMPORTANCEC_SCPLOWThe Typhlocybinae and Eurymelinae leafhoppers differ significantly in their symbiotic communities. This is undoubtedly due to their different diets, as Typhlocybinae insects feed on parenchyma, richer in nutrients, while Eurymelinae, like most representatives of Auchenorrhyncha, consume sap from the phloem fibers of plants. Our work presents comprehensive studies of 42 species belonging to two above-mentioned, so far poorly known Cicadomorpha subfamilies. Phylogenetic studies we conducted confirm that the insects from the groups studied have a common ancestor. Since obligate symbionts, having a reduced genome, may affect the reduction of their hosts adaptation to changing environmental conditions, e.g. temperature, and facultative microbiomes may influence the increase in such adaptation and expansion of host niche space. Therefore, Typhlocybinae species may show greater resistance to future climate change than representatives of the Eurymelinae. The research that considers the role of ecological niches in microbiome composition is essential in the era of climate change.